Work clamping fixture



L. l. KAPLAN E'I'AL WORK C'LAMPING FIXTURE Feb. 12, 1952 2 SHEETSSHEET 2 Filed Oct. 25, 1948 Patented Feb. 12, 1952 WORK CLAMPING FIXTURE Leo I. Kaplan, Detroit, and Gustav von Iteis, Grosse Pointe, Mich., assignors to Detroit Broach Company, Detroit, Mich., a corporation of Michigan Application October 25, 1948, Serial No. 56,304

6 Claims.

This invention relates generally to fixtures and refers more particularly to improvements in work clamping fixtures.

One of the objects of this invention is to provide a work holding fixture having means enabling a work piece to be rigidly clamped to a work table with such effectiveness that the work will not move, cramp or deflect from its preselected position even when under abnormal cutting loads as, for example, when a hard spot is encountered or when an unusually deep out is taken.

Another feature of this invention is to provide a work holding fixture designed for easy and rapid loading and unloading. This is important as it renders it possible to employ the fixture in instances where extremely high production is required.

Still another object of this invention is to provide a work holding fixture which does not obstruct easy chip removal and permits free flow of coolant to the cutting teeth of the tool or tools employed to fashion the work while held by the fixture.

A further object of this invention is to provide a work holding fixture of the above general type composed of a relatively few simple parts capable of being readily assembled and installed on metal working machines.

The foregoing as well as other objects will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, wherein:

Figure l is a plan view partly in section of a work clamping fixture embodying the features of this invention;

Figure 2 is a sectional view taken substantially on the plane indicated by the line 22 of Figure 1;

Figure 3 is a sectional view taken on the plane indicated by the line 3-3 of Figure 2;

Figure 4 is a sectional View taken substantially on the plane indicated by the line 4--4 of Figure 1;

Figure 5 is a sectional view taken on the line 5-5 of Figure 3;

Figure 6 is a sectional view taken substantially on the line 6-4 of Figure 5; and

Figure '7 is a sectional View taken on the plane indicated by the line 7-1 of Figure 6.

It will be understood as this description proceeds that the work holding fixture is not restricted for use in connection with any specific type of metal working equipment, and moreover, is not limited to clamping work of any particular nature. However, for the purpose of 2 illustrating the present invention, the fixture is shown in connection with a conventional type of vertical broaching machine for clamping forged connecting rod assemblies while the cap sections are severed from the body sections. A typical forged connecting rod assembly is shown by dot and dash lines in the drawings as comprising a body section III and an integral cap section II. The cap section H cooperates with the adjacent end of the body section to provide a bearing for receiving a part of a crankshaft and the opposite end of the body section is bored to provide an opening [2 for receiving a wrist pin of the type usually provided for pivotally connecting the rod to a piston.

One vertical type of orthodox broaching machine is indicated generally by the reference numeral [3 and comprises a table I 4 having a vertical column l5. A suitable slide it issupported for vertical movement on the column and a pair of broaches I! is carried. by the slide with the cutting teeth extending toward each other in a common vertical plane. As shown particularly in Figure 1 of the drawings, the adjacent edges of the cutting teeth on the opposed broaches are spaced laterally from each other a suificient distance to enable severing the cap section I I from the body section it! of a forged connecting rod supported on the table it.

The work piece or connecting rod is actually supported on the table I 4 by a work clamping fixture [8 having a base l9 suitably secured to the table l4 and having a recess 20 in the top surface for accommodating the forged connecting rod or work piece. A projection or rib 2| is formed on the lease IE1 at the inner side of the latter and extends between the broaches H. The top surface of the rib or projection forms a continuation of the base of the recess 20, and the opposite sides of the rib are formed with vertical slots 22 providing clearance spaces for the teeth on the broaches.

The top surface of the rib 2| cooperates with the base of the recess 20 to form a bearing face on which the cap end of the connecting rod is adapted to be supported. Lateral shifting movement of the cap end of the rod in the recess 20 is prevented by hardened blocks 23 respectively secured in recesses 24 formed in the base l9 at opposite sides of the recess 20. As shown in Figure 6 of the drawings, the adjacent ends of the blocks respectively engage opposite sides of the cap end of the connecting rod to effectively hold the latter against lateral shifting movement. Attention is called to the fact that the bearing blocks engage a connecting rod outwardly beyond the slots 22 so as not to interfere with the operation of the breaches l1. The wrist pin end of the connecting rod is positioned by a pin secured to the base I9 in the manner shown in Figure 4 of the drawings and having the upper end projecting above the base for engagement in the opening I2 formed in the wrist pin end of the connecting rod. It follows from the above that the connecting rod is accurately located and positively held against lateral and fore and aft shiftin movement relative to the base I9.

In order to effectively clamp the cap end of the connecting rod against the base [9 during the broaching operation, the following mechanism is provided. This mechanism comprises a shaft 26 journalled in a .block 21 which in turn is secured to the base 19 by the fastener elements 28. The inner end of the shaft 26projects beyond the adjacent end of the journal 21 and is provided with a laterally outwardly extending arm 29 having a pad 30 on the free end adapted to engage the top of the cap end of the connecting rod in one angular position of the shaft 26 and adapted to be swung free from the connecting rod in another angular position of the shaft 26 to enable unobstructed loading and unloading of the fixtures. It will be noted from Figure 1 of the drawings that the width of the pad is less than the distance between the teeth on adjacent edges of the broaches, so as not to interfere with the action of the latter during the interval the cap section of the rod is severed from the body section.

The outer end 3| of the shaft 26 1s reduced.

and projects beyond the adjacent end of the journal 21. A second arm 32 is keyed or otherwise secured at one end to the reduced portion 31 of the shaft, and is secured in place by a clamping nut 33 threaded on the reduced end of the shaft. The arm 32 extends laterally outwardly from the shaft in a direction opposite the direction of the arm 29 and is provided with an upwardly extending manually operable grip 34. The purpose of the grip 34 is to enable the pad 30 to be readily swung from its inoperative position out of registration with the work or connecting rod to an operative position wherein it engages the top surface of the work piece or connecting rod. This greatly facilitates loading and unloading of the fixture.

The clamping mechanism also embodies a lever 35 pivoted at its lower end on a pin 36 for swinging movement about an axis extending substantially parallel to the axis of the shaft 26. The upper end of the lever has a hardened cam member 31 suitably secured thereto in a position to engage the free end of the arm 32 at the underside of the latter, and thereby acts as a stop to hold the pad 30 against the work piece. It will further be observed from Figure 2 of the drawings that the cam surface on the member 32 is shaped to cooperate with the free end of the arm 32 to rock the shaft 26 in a direction to forcibly clamp the work piece against the support I9 by the arm 29 when the lever 35 is swung in the direction indicated by the arrow 36 in Figure 2 of the drawings. The arrangement is such that regardless of variations in the height of the work piece, the latter is effectively clamped against the support during the broaching operation.

Referring again to Figure 2 of the drawings, it will be noted that the lever 35 may be swung in the opposite direction to its dot and dash line position where the cam member 31 is disengaged from the arm 32 permitting the shaft 26 to be readily rotated by the manually operable grip 31 to a position wherein the pad 30 on the arm 29 is not only released from clamping engagement with the work piece, but is also spaced sufficiently to one side of the latter to enable the work piece to be readily removed from the fixture and to permit another work piece to be inserted into the fixture. The lever 35 is operated by power means in the form of a fluid pressure motor-comprising a cylinder 39 and a piston 49 reciprocably mounted in the cylinder. An opcrating rod is suitably secured to the piston 40 and extends through a bore 4| formed at one end of the piston for connection with the lever 35 intermediate the ends of the latter. This connection comprises a yoke 42 threadably mounted on the free end of the rod and having laterally spaced fingers 43 extending along opposite sides of the lever 35. The fingers 43 are formed with aligned openings therethrough for receiving a pin 44, and the latter also projects through a suitable opening formed in the lever 35. Fluid under pressure is alternatively admitted to and exhausted from the cylinder 39 at opposite ends of the piston 40 under the control of a suitable valve not shown herein. The valve may be manually or automatically operated, depending upon the type of equipment with which the fixture is used. In any case it is important to note that when the operating lever 35 is in its operative or full line position shown in Figure 2 of the drawings, the fluid under pressure in the cylinder 39 acts on the piston 40 tending to continue swinging movement of the lever 35 in the direction of the arrow 38 and thereby assures the application of a continuous clamping pressure against the work piece by the pad 30 during the broaching operation. In other words there is no definite stop restricting the extent of movement of the piston on its clamping stroke, and as a consequence, the work piece is rigidly clamped to the support l9 regardless of variations in the height of the work piece.

What we claim as our invention is:

l. A work clamping fixture comprising a frame including a support for a work piece, a rock shaft mounted on said frame and of a length to hold the axis thereof relatively fixed in position, a rock arm on one end of said shaft, an axially extending clamping pad at the free end of said rock arm adapted to register with the work piece when on said work support, an oppositely extending rock arm on the other end of said shaft, a handle for manually rocking said shaft through a sufiicient angle to clear said first mentioned rock arm from said work support and for moving it into engagement with the work when placed on said support, a third rock arm movable in the plane of said second mentioned rock arm and mounted on said frame about an eccentric axis being normally in a position out of the path of said second rock arm, and a cam carried by the free end of said third rock arm for engaging said second rock arm when said pad on said first rock arm is engaged with the .work piece being adapted to compensate for variation in thickness of the work piece and to place high clamping pressure thereon.

2. The construction as in claim 1 provided with means for accurately positioning the work piece on said work support prior to the clamping thereof.

3. The construction as in claim 2 in which the positioning means includes a pin on said frame engaging a bearing in the work piece, and side bearings for preventing rotative displacement about the axis of said pin.

4. The construction as in claim 3 in which the supporting bearing and the clamping and positioning means clear the work piece on opposite sides thereof for machining operations.

5. A Work clamping fixture comprising a frame including a support for a work piece, a rock shaft mounted on said frame and of a length to hold the axis thereof relatively fixed in position, a rock arm on one end or" said shaft, an axially extending clamping pad at the free end of said rock arm adapted to register with the work piece when on said support, an oppositely extending rock arm on the other end of said shaft, a handle for manually rocking said shaft through a sufficient angle to clear said first mentioned rock arm from said support and for moving it into engagement with the work piece when placed on said support, a third rock arm movable in the plane of said second mentioned rock arm and mounted on said frame about an eccentric axis bein normally in a position out of the path of said second rock arm, a cam carried by the free end of said third rock arm for engaging said second rock arm when said pad on said first rock arm is engaged with the work piece being adapted to compensate for variation in thickness of the work piece and to place high clamping pressure thereon, and a fluid pressure motor for actuating said third rock arm and maintaining the same maximum clamping pressure in various final positions of said third rock arm.

6. A Work clamping fixture comprising a frame including a support adapted to hold a pitman rod work piece having integral wrist pin and crank pin bearing portions, a rock shaft mounted on said frame and of a length to hold the axis thereof relatively fixed in position, a rock arm on one end of said shaft, an axially extending clamping pad at the free end of said rock arm adapted to register with the work piece when on said support, an oppositely extending rock arm on the other end of said shaft, a handle for manually rocking said shaft through a sufficient angle to cl ar said first mentioned rock arm from said support and for moving it into engagement with the work piece when placed on said support, a third rock arm movable in the plane of said second mentioned rock arm and mounted on said frame about an eccentric axis. being normally in a position out of the path of said second rock arm, a cam carried by the free end of said third rock arm for engaging said second rock arm when said pad on said first rock arm is engaged with the Work piece being adapted to compensate for variation in thickness of the work piece and to place high clamping pressure thereon, and means for accurately positioning the pitman rod work piece on said support prior to clamping thereof, said positioning means including a pin on said frame engaging the Wrist pin bearing portion, and side'bearings for preventing rotative displacement of the work piece about the axis of said pin, said pin positioning the crank pin bearing portion on said support with the opposite sides thereof clearing said support, clamping pad and side bearings to permit the severing of said opposite sides to form a detachable cap for said crank pin bearing portion.

LEO I. KAPLAN. GUSTAV VON RE IS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,506,424 Hancock Aug. 26, 1924 1,974,660 Sinclair Sept. 25, 1934 2,190,067 Hart Feb. 13, 1940 

